(1) Field of the Invention
The present invention relates to power-saving control technology used in image forming devices, such as printers, copiers, facsimile machines, and multi-functional peripherals having the functions of printers, copiers, and facsimile machines.
(2) Description of the Related Art
In order to avoid wasteful consumption of power, some conventional image forming devices automatically switch to power-saving mode by shutting down power supply to a printer engine and a control panel when they have not received data from outside for a predetermined time period or longer, when no panel operation has been performed for a predetermined time period or longer, etc. After entering the power-saving mode, these image forming devices cancel the power-saving mode and return to normal mode when they receive data from outside, when a user performs a panel operation, etc.
Document 1 discloses, as one type of power-saving mode, deep sleep mode that makes use of a received packet. During the deep sleep mode, electrical conduction is always established between an image forming device and a LAN controller built in the image forming device, even when the main power of the image forming device is turned off. When the received packet includes a print request, the image forming device performs printing as requested. After the printing, if a first predetermined time has elapsed without the image forming device receiving any request from outside, the image forming device performs control so as to return to sleep mode. On the other hand, when the received packet does not include a print request, if a second predetermined time, which is shorter than the first predetermined time, has elapsed without the image forming device receiving any request from outside, the image forming device performs control so as to return to the deep sleep mode. In the above manner, after the deep sleep mode is cancelled, the time period for which the normal mode lasts is shortened when the received packet does not include a print request, thereby reducing a power consumption.
Incidentally, in order to connect computers and image forming devices (peripheral devices of the computers) to a network such as the Internet so as to allow the computers and the image forming devices to communicate with one another, a dynamic host configuration protocol (DHCP) server or a domain name system (DNS) server is required. The DHCP server automatically issues IP addresses and the like. The DNS server converts domain names into IP addresses. In light of the above, Bonjour, which does not require the DHCP server or DNS server, has been developed. Representative functions of Bonjour include automatic assignment of IP addresses and host names, and automatic discovery of services. When a device is connected to a Bonjour network, an IP address is automatically assigned to the device, and available services are notified to the device together with corresponding host names. Here, preset device names are used as host names. Bonjour uses multicast. The device sends, by multicasting, an inquiry to all the other devices connected to the network about which servers provide a desired service. In response, one or more servers that provide the desired service notify the device to that effect.
However, according to the technology disclosed in Document 1, the image forming device returns to the normal mode from the power-saving mode even in a case where the received packet does not include a print request. Furthermore, the technology disclosed in Document 1 is such that, when Bonjour is employed, the image forming device returns to the normal mode from the power-saving mode also in a case where the image forming device receives, from another device, a request that is not directly related to printing. Therefore, in either case, there is a problem of wasteful consumption of power in the image forming device.    Document 1: JP Patent Application Publication No. 2006-025212